Chickenpox

The incubation period, the length of time from exposure to the virus to developing the
condition, is two to three weeks. If someone in the house has chickenpox, the likelihood of
someone else in the house catching it, who has not already had it, is as high as 90% - 9 out
of 10.

Chickenpox usually affects children and starts with a slightly raised temperature, and feeling
under the weather, along with the development of red spots, mainly on the body and face.

The spots appear over a few days and progress from being red spots to forming blisters, which
eventually burst, dry, and crust, ultimately to heal. The spots are very itchy, and if the child
scratches and infects them they will leave scars.

By the time the spots have stopped forming and are dried over and the temperature has fallen
back to normal, the child is no longer infectious. Usually this takes about a week, until then
they should remain off playgroup or school.

Chickenpox does not usually make children very ill, and for most the main problem is the
itchiness. Your doctor will not normally need to see the child, but you should let him know that
the child has had it. Occasionally more serious complications can occur, and if a child does not
appear to be following the above course it is worth speaking to your doctor.

Having had chickenpox most people are immune and can not catch it again. However the virus
particles remain dormant in your nervous system and can, at a later stage, cause
shingles. As a result of the
large numbers of people who catch chickenpox as children, 90% of adults are immune.

People with chickenpox or shingles
should stay away from others who have not had chickenpox until their rashes have dried up. This
especially applies to staying away from people who have depleted immune systems (including
people: on steroids; on cancer drugs; on immunosuppressant drugs for transplants; or with AIDS).
These people are said to be immunocompromised and cannot fight off an infection as well as the
rest of us. Another group who are at higher risk is pregnant women and newborn babies.

There is now a chickenpox (varicella) vaccine. This is not used in all countries. It can be
given as a protective measure to immunocompromised people, especially children with leukaemia or
organ transplants.

For people who are not immune and who are exposed to the virus, there is a way of using the
antibodies that someone else has made against an infection. This is called passive
immunisation.

An injection is made up from the protein in people's blood which fights off infections
(immunoglobulin). In the case of chickenpox it is made from pooled serum from blood donors who
have recently had chickenpox or shingles. In the UK it is standard practice for all blood donors
to be tested for, and be clear of HIV, Hepatitis B, and Hepatitis C.

This product is known as Human Varicella-Zoster Immunoglobulin (VZIG). Its
supplies are limited, as a result of the small number of suitable donors, and thus it can only
be given to those at greatest risk and in whom it has been shown that it is likely to be
effective.

VZIG is recommended for use in people who fit into all three of the following groups:

A clinical condition that increases the risks of developing a severe response to the
varicella virus, such as:

Immunocompromised (people on steroids; on cancer drugs; on immunosuppressant drugs
for transplants; with AIDS; etc.)